/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlinePresenceInterface.h
the stringified version of the enum passed in
namespace EOnlinePresenceState { const TCHAR * EOnlinePresenceState::ToString ( [EOnlinePresenceState::Type](API\Plugins\OnlineSubsystem\Interfaces\EOnlinePresenceState__Type) EnumVal ) }